The documents, Greenpeace said, showed that U.S. trade negotiators had pressed their European counterparts to loosen important environmental, consumer protection and other provisions.

But American and European trade officials, while not denying the validity of the materials, insisted Monday that the documents — 248 pages, which Greenpeace said amounted to two-thirds of the latest negotiating text — merely represented negotiating positions, and that the criticisms by the environmental groups were off base.

Still, the disclosures and criticisms are unlikely to speed the talks, which already seem to have little chance of making progress until after the United States elects its next president in November — if even then, given how rancorous foreign trade has become in the U.S. political debate.

The deal, known as the Transatlantic Trade and Investment Partnership, would cover a huge range of goods and services between the world’s largest national economy and the world’s largest single market, spanning telecommunications, agricultural products, textiles, intellectual property, financial services and regulatory compatibility.

In one of the negotiating documents — a chapter on “Sanitary and Phytosanitary Measures” — U.S. negotiators made repeated references to improving cooperation over “products of modern agricultural technology.”

The U.S. proposal “clearly indicates their pressure to get rid of trade barriers for genetically modified organisms,” Jorgo Riss, director of Greenpeace’s European unit, said in a telephone interview. The proposal also refers to a “Global Low Level Presence Initiative,” which Riss said was a U.S.-backed initiative to gain global acceptance of agricultural exports containing traces of unauthorized genetically modified organisms.

In general, opposition to genetically modified organisms, or GMOs, tends to be stronger in Europe than in the United States. Riss acknowledged there was no direct reference to GMOs in the documents but said the language clearly was aimed at promoting their acceptance.

Negotiations over the accord began in July 2013; and the latest round, the 13th, concluded Friday in New York.

After decades of free-trade orthodoxy, there has been growing resistance to further liberalizing the movement of goods, services, capital and labor, fueled by fears that the benefits have flowed disproportionately to corporations, investors and well-educated workers — and that the harm to less-educated workers has outweighed the benefits to consumers. In the United States, the two leading contenders for the presidency, Donald Trump and Hillary Clinton, have both expressed skepticism about trade deals.

Last month, President Barack Obama traveled to a manufacturing fair in Hanover, Germany, to join German Chancellor Angela Merkel, urging the acceleration of negotiations. While expressing confidence that the talks would wrap up this year, Obama, who will leave office on Jan. 20, acknowledged that “time is not on our side.”

That was an implicit acknowledgment of the skepticism held by Clinton, the Democratic front-runner in the race to succeed him, toward multilateral trade agreements.

So Monday’s revelations — like the Panama Papers, which disclosed vast amounts of information about the offshore wealth held by global elites — could further complicate efforts to finalize the sensitive trade talks, even if there did not appear to be big bombshells within the documents.

Perhaps the most sensitive issues are outlined in a document describing the “tactical state of play” on both sides. The document says, for example, that different approaches to animal testing “remain irreconcilable.” Many U.S.-made skin cosmetics use ultraviolet filters, for which animal testing is used to assess safety; the European Union bans such testing on animals.

The Americans expressed “particular sensitivity” over tariffs on dairy, sugar and tobacco, while the Europeans wanted restrictions on wine labeling included in the accord.

Greenpeace accused the U.S. negotiators of trying to weaken environmental protection standards; of taking a laxer approach to product regulation than the Europeans; and of trying to give corporate lobbyists greater say in decision-making.

“These leaked documents confirm what we have been saying for a long time: TTIP would put corporations at the center of policymaking, to the detriment of environment and public health,” said Jorgo Riss, director of Greenpeace EU. “We have known that the EU position was bad, now we see the U.S. position is even worse.”

The Sierra Club, which has published a critique of trade deals, said it was dismayed that the words “climate change” were “not mentioned once in the 248 pages.”

The group said the documents showed the Americans were proposing to allow corporations to “petition” for the repeal of a regulation if it was “more burdensome than necessary to achieve its objective,” given its impact on trade. The documents also showed, it said, that the Europeans had proposed allowing certain environmental standards to be deemed “technical barriers to trade,” which could weaken labels requiring the disclosure of the climate footprint of a product or service.

The group also warned that the text included trade rules that could be used against “buy local” programs that support local clean-energy jobs in nearly two dozen U.S. states.

Although the leaks may have been embarrassing, officials on both sides tried to contain the fallout.

“The interpretations being given to these texts appear to be misleading at best and flat-out wrong at worst,” said Matthew McAlvanah, an assistant U.S. trade representative.

In a statement, he said the accord would “preserve, not undermine, our strong consumer, health, environmental standards, and position the U.S. and the EU to work together to push standards higher around the world.”

In a blog post, Cecilia Malmstrom, who as the European commissioner for trade is leading the 28-nation bloc’s negotiations with the United States, said that “many of today’s alarmist headlines are a storm in a teacup.”

Malmstrom said that the documents “reflect each side’s negotiating position, nothing else.” Referring to genetically modified organisms, which are of particular concern to many European consumers, she added: “No EU trade agreement will ever lower our level of protection of consumers, or food safety, or of the environment. Trade agreements will not change our laws on GMOs, or how to produce safe beef, or how to protect the environment.”